By such a vacuum cleaner which is known from international patent publication WO 92/03210 A1, air polluted with airborne particles, like liquid, dust and dirt is being moved by means of vacuum towards the separator. When rotating the separator, centrifugal forces are exerted on the airborne particles due to which the airborne particles are being moved away from the separator, whilst the cleaned air flows through the separator towards the air outlet opening. Relatively heavy particles will be separated from the air at a relatively low rotational speed of the separator. However, to be able to remove relatively light particles as well, a relatively high rotational speed is needed. At such a relatively high rotational speed, the heavier particles might be moved towards the separator in axial direction and hit the separator with a relatively large force. The heavier particles might damage the separator due to which an unbalance of the rotating separator might occur, which will negatively influence the performance of the vacuum cleaner, especially at high rotational speeds.